Continuous process for relaxing heat treatment and apparatus therefor

ABSTRACT

An improvement in a continuous process for the relaxing heat treatment of crimpable filaments, particularly potentially crimpable filaments which comprises passing the filaments overfed from a filament charging apparatus through an ejecter, wherein a heated fluid is ejected, to subject the filaments to pre-heating and fiber separation, spraying a heated fluid onto the filaments at right angles from their circumference in a low tension zone under a tension as low as 1 mg/denier or less to subject the filaments to relaxing heat treatment, and then passing the treated filaments through a heat treatment chamber to subject the filaments to thermal setting, and an apparatus therefor.

United States Patent [191 Chimura et al.

[111 3,724,038 1 Apr. 3, 1973 [54] CONTINUOUS PROCESS FOR RELAXING HEATTREATMENT AND APPARATUS THEREFOR [73] Assignee: Mitsubishi Rayon Co.,Ltd., Tokyo,

Japan 22 Filed: June23, 1971 21 Appl.No.:155,72 2

[30] Foreign Application Priority Data [58] Field of Search ..28/l.2,1.4, 72 HR, 72.1, 72.12

[56] References Cited UNITED STATES PATENTS 3,425,107 2/1969 Matsui etal 3,558,760 l/l97l Olson 3,644,968 2/1972 Elliott et a]. ..28/l.4 X

Primary ExaminerLouis K. Rimrodt Attorney-James E. Armstrong et al.

[57] ABSTRACT An improvement in a continuous process for the relaxingheat treatment of crimpable filaments, particularly potentiallycrimpable filaments which comprises passing the filaments overfed from afilament charging apparatus through an ejecter, wherein a heated fluidis ejected, to subject the filaments to pre-heating and fiberseparation, spraying a heated fluid onto the filaments at right anglesfrom their circumference in a low tension zone under a tension as low asl mg/denier or less to subject the filaments to relaxing heat treatment,and then passing the treated filaments through a heat treatment chamberto subject the filaments to thermal setting, and an apparatus therefor.

5 Claims, 4 Drawing Figures CONTINUOUS PROCESS FOR RELAXING HEATTREATMENT AND APPARATUS THEREFOR The present invention relates to animprovement in a continuous process for the relaxing heat treatment ofcrimpable filaments, particularly filaments having potentialcrimpability, and an apparatus therefor.

In general, so-called potentially crimpable filaments produced bysubjecting two or more polymer components to composite spinning or bycarrying out partial heating or cooling during the spinning of onepolymer are very weak in crimp developing power. Therefore, it isnecessary for obtaining uniform crimped yarn having a high bulkiness tosubject filaments to heat treatment under a tension as small aspossible. If the heat treatment is carried out at a high speed toincrease productivity, the constraining force exerted on the filamentsis increased by frictional resistance to air with increasing speed andthereby the development of crimps is remarkably obstructed. Therefore,the resulting crimped filaments have poor bulkiness. As a means forsolving such a problem, there is proposed in Japanese Pat. publicationNo. 15,582/ 1968 an apparatus for subjecting filaments to heat treatmentin a tensionless state in a heating cylinder wherein ejectors areprovided oppositely at its inlet and outlet.

However, in such an apparatus, when the filaments running at a highspeed pass through the outlet side ejector, the filaments are againsubjected to high tension in a heated state. Therefore, the developedcrimps are straightened and the level of crimp developing of thefilaments in a heated state is subject to wide fluctuations according toa slight disturbance of the heated fluid circulating through the outletside ejector. It causes uneveness of crimp and streakiness of dyedfabric. Further, it is very difficult to pass filaments through theopposite ejectors before the start of the operation. Thus, such anapparatus presents various problems in commercial operation.

It is therefore the principal object of the present invention to avoidthe difficulties heretofore encountered in the high speed relaxing heattreatment of filaments and to remove defects of prior art processes.

It is a further object to provide crimped filaments having a highbulkiness, crimp uniformity and excellent dye-eveness.

Another object of the present invention is to provide an improvedprocess for the continuous relaxing heat treatment of filaments and animproved apparatus for practising the process.

These and other objects and advantages of the invention will appear fromthe following description of the invention.

More particularly, the present invention is directed to a process forthe continuous relaxing heat treatment of filaments characterized inthat the filaments overfed from a filament charging apparatus are passedthrough an ejector to subject the filaments to preheating and fiberseparation, and a heated fluid isthen sprayed onto the filaments atright angles from their circumference in a low tension zone under atension as low as l mg/denier or less to subject the filaments torelaxing heat treatment, and the treated filaments are then passedthrough a heat treatment chamber to subject the filaments to thermalsetting.

Further, the present invention provides an apparatus for the continuousrelaxing heat treatment of filaments characterized in that an ejector isprovided on the inlet side of a heat treatment chamber and a spray meansis provided between said ejector and said heat treatment chamber forspraying heated fluid onto the filaments at right angles from theircircumference.

The present invention will be explained in detail referring to theaccompanying drawings in which:

FIG. 1 is an axial cross sectional view of an embodiment of theapparatus of the present invention;

FIG. 2 is a sectional plan view of a spray means (ring) used in theapparatus of FIG. 1;

FIG. 3 is a graph showing the tension distribution in the runningfilaments in the apparatus of FIG. 1; and

FIG. 4 is a graph showing the temperature distribution in the apparatusof FIG. 1 and (1) shows the temperature distribution in the direction ofthe central axis while (2) the temperature distribution in the radialdirection.

In FIG. 1, a heat treatment apparatus 1 consists of an ejector 3, a heattreatment chamber 5 having a heater (not shown) at its circumference anda hot gas spray ring 4 as coaxially provided between the ejector and theheat treatment chamber. Above said heat treatment apparatus 1, there areprovided a pair of supply rollers 2 and 2', while a pair of take-uprollers 7 and 7 are provided below the heat treatment apparatus.

Further, a cover plate 6 having a guide opening 17 at its center isprovided between the heat treatment apparatus 1 and the take-up rollers7 and 7 The cover plate 6 serves for preventing the take-up rollers 7and 7' from being heated by the hot fluid flowing out from the heattreatment chamber 5. Said supply rollers 2 and 2 are rotated at higherspeed than the take-up rollers 7 and 7 to overfeed the filament 9 in theheat treatment apparatus 1.

As is shown in FIG. 2, said spray ring 4 is made up of an outer ring 11and a porous metal inner ring 14, with these two rings being coaxiallyprovided. Two separators 12 and 12' serve for coupling these rings 11and 14 and for separating an annular space between the rings into twopressure chambers 13 and 13'. In the outer ring 11, there are providedducts l0 and 10' for introducing a heated fluid, which lead to thepressure chambers 13 and 13', respectively. The heated fluid blown intothe pressure chambers 13 and 13' through said ducts l0 and 10' ispressurized in these chambers and is then uniformly sprayed toward thecentral axis through the inner ring 14 as is shown by arrows in FIG. 2.The inner ring 14 may be of any type so long as the heated fluid can beuniformly sprayed through it. However, a 150 mesh porous metal ring isthe most preferable.

In the apparatus of FIG. 1, stretched filament 9 having potentialcrimpability is overfed in an appointed amount and runs between thesupply rollers 2 and 2' and the take-up rollers 7 and 7'. The filamentleaving the supply rollers 2 and 2 is first swallowed up into an ejector3. The filament 9 is subjected to thorough fiber separation andpreheating by a hot jet stream flowing through the ejector 3. Thetemperature of this jet stream is preferably about C for polyamide,about C for polyester and about C for polyacrylonitrile fiber. If thetemperature is too low,

preheating can not be sufficient and subsequent development of crimpsand thermal fixing will not become satisfactory. Also, if thetemperature is too high, the filament 9 is subjected to heat relaxing atthe throat 15 of the ejector under a high tension and crimp developingability is undesirably reduced.

The filament 9, which has been subjected to separating and preheating,then enters a low tension zone C formed on the boundary between a zone Awherein the speed of the ject stream is higher than that of the filament9 and a zone B wherein the speed of the jet stream is lower than that ofthe filament, as shown in FIG. 3. This low tension zone C has now beenfound by the present inventors as a result of their diverse study.

The tension in the zone A is due to the speed difference between therunning filament 9 and the jet stream in the ejector 3. The tensiondistribution in the zone A was obtained by blowing a jet stream into thezone from the ejector 3 and measuring the frictional force exerted onthe filament 9 while the filament is at a stand-still. The tensiondistribution in the zone B was obtained based on the analysis by a windtunnel test of the phenomenon that a frictional force generated by therelative velocity between the filament 9 and the atmosphere exerts onthe filament 9 as a tension. FIG. 3 has been obtained by linking thesetwo tension distributions to each other and shows the tensiondistribution of the filament 9 between the supply rollers 2 and 2' theheat treatment apparatus 1 the take-up rollers 7 and 7'.

The term, low tension zone C, used herein means a zone wherein thepotentially crimpable filament is under a critical tension required forthe filament to develop crimps, that is, a tension of l mg/denier orless.

If the filament 9 enters said low tension zone C, the cold air layerwhich lies between or around the constituent single fibers is destroyedby the heated fluid sprayed from the spray ring 4 as provided in saidzone C and is replaced by the heated fluid. Thus, the temperature of theatmosphere is kept high to effect heat exchange with the filament 9.Heat is rapidly transferred to the filament 9 and the temperature of thefilament 9 is readily increased because the heated fluid flows at rightangles to the filament 9. Therefore, the

filament 9 may develop crimps sufficiently and uniformly.

The filament 9 then develops further crimp uniformly and is subjected tothermal setting in the heat treatment chamber 5. The temperature in theheat treatment chamber 5 is made almost uniform both in the direction ofthe central axis 1 and in the radial direction 2 by the action of theheated fluid from said spray ring 4, as is shown in FIG. 4. Therefore,even if the filament 9 swings in the heat treatment chamber, dyeingstreakiness is not generated by a variation in heat history. Also, FIG.4 shows the temperature distribution at the jet stream in the ejector150C, a temperature of the heated fluid in the spray ring 300C and atemperature of the wall of the heat treatment chamber 300C.

The filament 9 leaving the heat treatment chamber is then taken up by abobbin 16 through the guide opening 17 of a cover plate 6, take-uprollers 7 and 7' and a guide 8.

As described above, according to the present invention, filaments havingself-crimpable potential are first passed through an ejector to effectpreheating and fiber separation and are then subjected to relaxing heattreatment in a specific low tension zone by spraying a heated fluid ontothe filaments at right angles from the circumference under a tension ofl mg/denier or less. Therefore, even if the running speed of thefilaments is remarkably high, the filaments can develop crimps uniformlyand sufficiently. Also, the temperature distribution in the heattreatment apparatus is made quite uniform by the action of said heatedfluid. Therefore, the streakiness caused by a variation in heat historycan be prevented and thorough thermal fixing can be effected.

Further, the apparatus of the present invention has many commercialadvantages, for example, in that it is simple in structure and is veryeasy to operate.

It will be clear that the present invention can be applied to not onlythe crimp development of potentially crimpable fibers but also thethermal fixing of the other crimped yarns.

The following examples will serve to illustrate the practice of thepresent invention in more detail. The terms, relaxation percantage,thermal shrinkage percentage, number of crimps and crimp percentage usedin these examples have the following definitions, respectively:

Relaxation percentage: A numerical value calculated according to theformula,

wherein V The circumferential speed of the supply rollers 2 and 2' V Thecircumferential speed of the take-up rollers 7 and 7' Thermal shrinkagepercentage:

A numerical value calculated according to the formula,

(l -1 H X wherein l,,: The length of the crimp developed yarn under aload of 0.2 g/denier I The length of the said yarn under said load afterthe yarn was subjected to dry heat treatment at C for 20 minutes Numberof crimps: Number of crimps/25 mm of the single fiber under a load of 2mg/denier Crimp percentage: A numerical value calculated according tothe formula,

wherein a: The length of the single fiber under a load of 2 mg/denier b:The length of said single fiber which has been further subjected to aload of 0.2 g/denier EXAMPLE 1 Two hundred seventy Denier/36 filamentunstretched yarn obtained by composite spinning at 290C of twopolyethylene terephthalate polymers having intrinsic viscosity [1;] of0.53 and 0.75, respectively, as measured in a 50 2 50 mixture ofdichloroethane and phenol at 35C was stretched to 3.85 times theoriginal length and was then subjected to continuous relaxing heattreatment using the apparatus of FIG. 1 at a supply speed of 600 m/min,a relaxation percentage of 20 a temperature of the air jet stream in theejector of 150C and the temperature'of the heated fluid in the sprayring of 250C and the wall of the heat treatment chamber of 250C. Theobtained crimped yarn was 75 denier/36 filaments and had very highbulkiness and excellent thermal stability and a number of crimps of 31.8per 25 mm and a thermal shrinkage percentage of 1.8

Said crimped yarn was then knitted into a 18 gauge plain knitted fabric.The obtained fabric was dyed with a disperse dye, Duranol Red GN (C.I.No. 60505). Thus, a dyed fabric having high bulkiness and a uniformsurface of knitted fabric was obtained and no streakiness was observedtherein.

EXAMPLE 2 Stretched 75 denier/34 filaments yarn obtained by subjectingtwo polycapramides having relative viscosity of 2.2 and 3.9,respectively, in sulfuric acid to composite spinning and then coldstretching to 3.2 times the original length was subjected to continuousrelaxing heat treatment using the apparatus of FIG. 1 at a speed of thesupply rollers of 600 m/min, a relaxation percentage of 32 percent, atemperature of air jet stream in the ejector of 100C, a temperature ofheated fluid (superheated stream) in the spray ring of 112C and atemperature of the wall of the heat treatment chamber of 100C. Thus,crimped yarn having a number of crimps of 52 per.25 mm, a crimppercentage of 50 percent and a shrinkage percentage after treatment inboiling water of 2.6 percent was obtained.

The crimped yarn was then knitted into a 18 gauge plain knitted fabric.The obtained fabric was dyed with Cibacet Blue F3R (C.I. No. 61505).Thus, a dyed fabric having high bulkiness and a uniform surface ofknitted fabric was obtained and no streakiness was observed therein.

COMPARATIVE EXAMPLE The same unstretched yarn as in Example 1 wasstretched 3.85 times theoriginal length and was then subjected torelaxing heat treatment using a known heat treatment apparatus, whereintwo ejectors are provided against the inlet and outlet for the filamentrunning through the heat treatment chamber and an outlet for exhaustingthe heated fluid is provided at the side wall of said heat treatmentchamber, at a speed of the supply rollers of 600 m/min, a relaxationpercentage of 20 percent, a temperature of air jet stream in the upperand lower ejectors of C and a temperature of the wall of the heattreatment chamber of 250C. The resulting crimped yarn showed a number ofcrimps of 20.2 per 25 mm and a thermal shrinkage percentage of 2.2percent. Said crimped yarn was then knitted and dyed in the same manneras in Example 1. The obtained dyed fabric was remarkably inferior tothat obtained according to the present invention in bulkiness anduniformity of knitted fabric and slightly inferior in dye-eveness.Further, the above-mentioned conditions may be changed, but such goodcrimped yarn as that of the present invention could not be obtained.

What is claimed is:

l. A process for the continuous relaxing heat treatment of filamentswhich comprises passing the filaments overfed from a filament chargingapparatus through an ejector, wherein a heated fluid is ejected, tosubject the filaments to preheating and fiber separation, spraying aheated fluid onto the filaments at right angles from their circumferencein a low tension zone under a tension as low as 1 mg/denier or less tosubject the filaments to relaxing heat treatment, and then passing thetreated filaments through a heat treatment chamber to subject thefilaments to thermal fixing of the fiber structure.

2. A process according to claim 1 wherein polyester filaments havingself-crimpable potential are subjected to heat treatment.

3. A process according to claim 1 wherein polyamide filaments havingself-crimpable potential are subjected to heat treatment.

4. An apparatus for the continuous relaxing heat treatment of filamentscharacterized in that an ejector is provided on the inlet side of a heattreatment chamber and a spray means is provided between said ejector andsaid heat treatment chamber for spraying a heated fluid onto thefilaments at right angles from their circumference, supply rollerslocated sequentially prior to the ejector, take-up rollers locatedsequentially after the heat treating chamber and at least one coverplate located between the chamber and take-up rollers.

5. An apparatus according to claim 4 wherein said spray means consistsof an outer ring and a porous metal inner ring, as arranged so that anannular space may be formed been the two rings, as well as a heatedfluid spray duct provided at the side wall of said outer ring, andseparators coupling the said inner and outer rings.

2. A process according to claim 1 wherein polyester filaments havingself-crimpable potential are subjected to heat treatment.
 3. A processaccording to claim 1 wherein polyamide filaments having self-crimpablepotential are subjected to heat treatment.
 4. An apparatus for thecontinuous relaxing heat treatment of filaments characterized in that anejector is provided on the inlet side of a heat treatment chamber and aspray means is provided between said ejector and said heat treatmentchamber for spraying a heated fluid onto the filaments at right anglesfrom their circumference, supply rollers located sequentially prior tothe ejector, take-up rollers located sequentially after the heattreating chamber and at least one cover plate located between thechamber and take-up rollers.
 5. An apparatus according to claim 4wherein said spray means consists of an outer ring and a porous metalinner ring, as arranged so that an annular space may be formed been thetwo rings, as well as a heated fluid spray duct provided at the sidewall of said outer ring, and separators coupling the said inner andouter rings.